study guide test 1
study guide test 1 kin 321
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This 7 page Study Guide was uploaded by Annmarie Jaghab on Sunday January 31, 2016. The Study Guide belongs to kin 321 at University of Miami taught by Dr.Jacobs in Winter 2016. Since its upload, it has received 46 views. For similar materials see in Physiology at University of Miami.
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Date Created: 01/31/16
KIN 321 TEST 1 NOTES Lecture 1: Bioenergetics -thermodynamics is the study of energy exchange -bioenergetics is a subset of thermodynamics -bioenergetics is energy exchange in the biological world -in biological systems, at most 20% of ATP is used for cellular work and the rest is being lost as heat -in mechanical systems, 20-25% is being used and the rest is dispersed to the environment -heat production increases the body temperature and rate of reaction increases that produce ATP for cellular work so that heat produced is not completely wasteful -at higher intensities muscle temperature gets higher and rates increase -sodium potassium pump requires ATP to move ions against their concentration gradients -ATP is required to dissociate thick and thin filaments -you go into rigor mortis when there is no more ATP because the reaction between thick and thin filaments cant occur without ATP -why does ATP change very little during exercise? if you deplete ATP the thick and thin filaments can’t dissociate. If that occurred in the diaphragm muscles or in the heart you would die -body is good at rebuilding ATP and fatiguing to assure you don’t run out of ATP -metabolism consists of the energy transformations -metabolism is the rate of heat production -indirect calorimetry is a measurement of oxygen consumption -direct calorimetry is hard to do (many things produce heat in surroundings so you have to account for variables like lamp or TV being on). Mostly use indirect calorimetry -bomb calorimetry looks at the kcals of energy in food based on the bonds broken -majority of energy we use feeds through aerobic pathways so that is why we measure oxygen consumption to see caloric food production -O2 or heat can be measured indirectly but O2 is easier to measure -except for protein, the kcal per gram inside the body and in a bomb calorimeter are the same. Why does the bomb calorimeter get 5.7kcal/g while the body gets only 4.2? protein has nitrogen and the body cannot use nitrogen as an energy source but the bomb calorimeter can use it to create heat -about 5 kcals per every liter of oxygen consumed -Respiratory quotient= CO2 produced/O2 consumed -respiratory quotient range is from .7 to 1 -why does a starving person have a low RQ? They are relying mostly on fat. Body is trying to maintain muscle and since you are not eating, you are not getting carbohydrates -as you move up in intensity the RQ increases because the higher the intensity, the more you rely on carbohydrates -during intense exercise, the RQ can actually exceed 1 but you are still only relying on carbohydrates. You get extra CO2 released from buffering Lecture 2: Macronutrients -protein serves for growth and development -regulation of metabolism: depending on what fuel source you take in, your body will be better at oxidizing that type of fuel -carbohydrates are mainly from plant sources -most of digestion and absorption happens in the small intestine -if you don’t have the enzyme to break lactose apart it will keep passing through the GI system and when it gets to the large intestine the bacteria in the colon feed on it -simple lipids are triglycerides which differ in fatty acid chain length due to carbon number. They are metabolized in twos during beta- oxidation to acetyl coA. -trans fat (aka partially hydrogenated oil) decreases good cholesterol, HDL -derived lipids are cholesterol -you consume triglycerides and after they are digested and absorbed they turn into a chylomicrons which is a lipoprotein and classified as a compound lipid -peptide bonds are strong and hard to break apart -protein contains nitrogen and is a building block for muscle so it is a last resort fuel source -moderate alcohol intake (1 glass of wine or 1 beer a day) shown to slightly increase HDL-C -blood flow and incoming macronutrients from intestines goes to the liver first because the liver is critical for maintaining blood glucose concentration by storing glycogen. When no glucose is coming from the gut, the liver needs to supply it -gastric emptying: stomach is a holding tank and doesn’t absorb many things until after it passes the stomach and goes to the small intestine -stomach can extend when fed. When you fill the stomach there is recoil and it wants to go back to being 50ml -to enhance gastric emptying you need to keep up with sweat rates -method of measurement for gastric emptying? People ingest a fluid with a dye and the dye will only disappear if it leaves the stomach -gastric emptying increases exponentially with increasing gastric volume -establish a large volume of fluid before exercise and then every 15 minutes drink but if you cannot you drink a larger amount less frequently -increase the energy content, decrease energy rate because the more calories the harder it is for ingestion -fruit juices should not be ingested during exercise, they will stay in the stomach too long -high exercise intensity and being dehydrated both decrease emptying rate -want 30-60g CHO per hour of a 6-8% solution ingested at a rate of 600-1200ml/hour during exercise. This is about 1g per minute. -the max rate the body can oxidize ingested carbohydrates is 1-1.3g per minute -bile emulsifies lipids to break them into smaller droplets -pancreas releases sodium bicarbonate (a base that neutralize the highly acidic contents of the stomach) and other pancreatic juices -carbohydrate digestion mainly in the small intestine -don’t need to know enzymes -fatty acid chains group together to form droplets called micelles -protein digestion mainly occurs in the stomach and continues in the small intestine -protein digestion ends at epithelial cells because they can absorb individual amino acids. -carbohydrates and lipids digestion is completed in the lumen whereas protein digestion ends in the epithelial cells -protein digestion is harder and metabolic rate increases -intestines have folds that increase the surface are of the intestine by 3x -each circular folds have villi which increase the surface area another 10 fold -each villi has its own veins and arteries going through them -fats enter the lymph system before they enter the blood which also have an extension into the villi so they take longer to ingest (2-4 hours before they get into blood) -monosaccharides and amino acids can get into the blood as quickly as 15 minutes after ingestion -this is why people shouldn’t ingest fat before and after exercise to improve performance -we already have plenty of fat so it is of limited use for exercise -SGLT-1 is in the small intestine and moves glucose and galactose -active absorption is the fastest means of transport and uses ATP -fructose moves by facilitated transport and does not use ATP -glucose, galactose, and sodium (along with water with them) can also move through SGLT-1 -amino acids are actively absorbed via specific transporters -water absorption is dictated by an osmotic gradient. Low to high osmolality (always goes to where there are more particles so it can dilute something down) -sea water would increase the rate at which you dehydrate Lecture 3: ATP, CP, and Glycolysis -as soon as there is a slight drop in ATP, metabolic systems increase to produce ATP -wingate test: 30 seconds all out on a bike. It relies on both oxidative and nonoxidative sources -store a lot more creatine phosphate than ATP (3-6 times more) -you don’t produce lactate when you have a lack of oxygen (that is what yeast do) -during slow glycoysis you don’t need to produce lactate because pyruvate production=pyruvate oxidation and the rate of NAD+ regeneration via mitochondrial shuttles is adequate -red blood cells constantly produce lactate because they lack a mitochondria so they always take in glucosepyruvatelactate. They cannot oxidize the lactate. -fast twitch type IIB fibers have high glycolytic capacity and low mitochondrial levels -slow twitch fibers type I have high oxidative capacity and high mitochondrial volume and can oxidize lactate well -lactate is not a dead end metabolite, it is a preferred fuel source. Once lactate is produced it can be oxidized within the same muscle it is produced, at a different neighboring muscle or the heart (which can oxidize lactate very quickly), or in the liver to be used in gluconeogenesis -about an hour or so the legs start to run out of muscle glycogen and lactate can be used to donate carbohydrate from inactive muscle to active -for 2 hours cycling, lactate was infused in people with fluids and when they walked to the bathroom to urinate, just walking there got the lactate levels back down -when you load the muscle with lactate the body uses it -why is the muscle preferring to use lactate over glucose? Because glucose needs investment of 2ATP to be used but to use lactate there is no ATP investment. So net ATP is greater when you use lactate instead of glucose -why was the use of muscle glycogen not effective by giving more lactate? Because the muscle glycogen is preferred since it is already in the muscle so the muscle prefers to use it since it is easily accessible. -if there is less demand downstream the liver doesn’t need to kick out as much glucose to help that demand -in the cytosol you need NAD for glycolysis -intracellular lactate shuttle regenerates NAD+ more quickly and also shuttles a substrate (pyruvate) into the mitochondria for ATP production) -rapid rates of glycolysis from intense exercise is what produces hydrogen ions and lowers the pH which gives you that feeling in your muscles. Lactate actually helps get rid of these hydrogen ions thereby acting as a buffer. If you can’t produce lactate the burning would be even worse. Lecture 4: Lipid Metabolism -majority of fats are outside the muscle. To use it, it must be transported to the muscle -once it is delivered to the muscle, it has to be transported to the mitochondria because that is where lipid oxidation occurs -re-esterification is attaching the glycerol backbone back on to make it a triglyceride again -epinepherine primarily helps you move fats -epinepherine binds to it’s receptor which relies on CAMP to then send a second messenger cascade down to stimulate HSL (hormone sensitive lipase, breaks lipids apart) -Monoglyceride lipase breaks off one fatty acid -glycerol in the blood is a good marker of the rate of lipolysis -insulin (storage hormone, when insulin is high you try to store fat) and epinephrine (stress hormone) have opposing effects -insulin triggers phosphodiesterase which breaks CAMP to AMP so it is a potent inhibitor of glycolysis -what is the purpose of decreasing the proportion of fatty acids re- esterified? At rest you re-esterify more fats because you don’t need them but when you go from rest to exercise there is an increase in metabolic rates so more fats go out into the blood -increase in lipoloysis is a slow process -free fatty acids are not really free, they are loosely bound to albumin. Need to have albumin delivered to the fat tissue -as you move up in exercise intensity, blood flow is shunted to active skeletal muscle -high intensity exercise means you have high levels of epinephrine so you will break down many fats but this will be counteracted by a lack of blood flow so mostly the fat will be re-esterified. -fat is an important fuel source for muscle in recovery -muscle and cardiac tissue prefer free fatty acids (because there is no lipolysis required) -uptake of fatty acids by skeletal muscle correlated with plasma concentration is NOT passive diffusion. -lipid uptake graph increases and then stops increasing because transporter proteins are already fully saturated -FAT/CD36 increase during and after exercise -FABP directs the fat to where it needs to go -fatty acid transporters increase with high fat diets of about 50-60% fat -to activate the fatty acid, you attach a CoA and it either goes into storage or oxidation -first step in moving fatty acids across is moving CoA off and attaching a carnitine, done by CAT1 (outer mitochondrial membrane) -CAT2 sits inside the matrix (inner mitochondrial membrane) and reattaches a coA -CAT 1 is the rate limiting enzyme -beta oxidation: take fatty acids with a long carbon chain and with every turn of the cycle 2 carbons come off as acetyl coA and that acetyl coA goes into the TCA/Kreb’s cycle. With every turn of the cycle two reducing equilivilents are produced, FADH and NADH which both go to the electron transport chain -when products of beta oxidation drop in concentration, beta oxidation will be stimulated -store lipids in the muscle (IMTG) for recovery purposes. It wants to rebuild muscle glycogen rapidly. Any glucose coming into the muscle, you want to convert it to glycogen -during exercise RER values increase (more carb usage) and then in recovery bout, RER values go down (more fat usage) -intensity should not be the primary concern for weight loss. It should be maximizing the amount of calories you expend. Lecture 5: Amino Acid Metabolism and Exercise Metabolism -resistance athletes need a greater intake of protein to increase protein synthesis -endurance athletes need a greater intake of protein also to replace the lost amino acids -if you try to increase muscle mass and don’t take enough protein your body will break down muscle to keep the amino acid pool up -the carbon skeleton of the amino acid is useful as a fuel source -you strip off and dispose of the nitrogen -amino acids are a fuel source of last resort -fasting and prolonged exercise (over 90 minutes) is when amino acid stores get tapped into -strip the amino group off and you get alpha ketoglutarate which goes to TCA cycle -transamination involves glutamate. Take the amino group and move it to pyruvate -pyruvate with an amino group becomes alanine -dispose of nitrogen through the use of the urea cycle. Occurs in liver and eventually uses the liver -oxidative deamination forms ammonia and then this combines with CO2 which becomes carbonyl phosphate -BCAA’s are more abundant and in high concentration in blood so they go through transamination to produce glutamate and the carbon skeleton is oxidized -deamination only occurs in mitochondria in the liver -transamination occurs in many tissues across the body -the liver cannot produce glucose quickly through gluconeogenesis. It is a slow pathway. It is a starvation pathway -fructose 1,6 bisphosphatase reverses the PFK step -glucose 6 phosphatase breaks the phosphate off to give you glucose -two fates for glucose: 1) storage 2) oxidation -epinepherine is a stress hormone -glucagon is a starvation hormone -high hydrogen ion concentration inhibits glycolysis -absorption of fat from gut takes 2 to 4 hours so most of the fat comes from the breakdown of adipose triglycerides -high rates of glycolysis inhibit CAT1 -glycogen stores water with it (3x weight in water) which makes them less efficient -higher intensity, more rapid you have to resupply ATP -carbs can produce acetyl coA more rapidly, so that is why it is a preferred fuel source during exercise -women rely more on fat for lower intensity exercise than men do, but at higher intensities there is no difference between men and women -as you increase intensity, you rely more on carbohydrates and less on fat -during higher intensities you start using more fast twitch fibers since they are more glycolytic -as you increase exercise duration you start using more from the plasma and less from glycogen and IMTG -hormonal reason for the liver to reduce the breakdown of glycogen? Insulin elevation -same power output=same absolute intensity -as people get trained, their vo2 max goes up -relative intensity: putting them at the same workload relative to how hard they feel the workload is -do people need to consume less carbohydrates in the trained state since they are better at using fat? No because the pattern of fuel use is really unaltered in terms of relative intensity. So they should actually be consuming more carbohydrates.
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